High-frequency lamp



Feb. 1- *9 H. c. RENTSCHLER HIGH'FREQUENCY LAMP Filed'Feb. 21, 1923 INVENTOR HARVEY C. REN'TSCHLEE.

. ATTORNEY Patented Feb. 1, 1927.

HARVEY CLAYTON BENTSCHLER, OF EAST PATENT OFFICE.

ORANGE, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.'

HIGH-FREQUENCY LAMP,

Application filed February 21, 1923. Serial No. 620,353.

I This invention relates to incandescent lamps, more especially to lamps adapted for use in concentrating light upon an object,

picture projectors, search such as in motion lights and the like.

It is an object of my invention to rovide an incandescent lamp having a re ractory body adapted to be heated by an are or electrical discharge generated y high frequency alternating currents or high fre-r quency electrical oscillations.

Another object of my invention is the provision of an incandescent lamp having two disks of refractory material arranged parallel and which are adapted to become] incandesced by an arc or electrical discharge operated between the same.

Another object of my invention is to provide an incandescent lamp having electrodes 2 therein which are brought to incandescence by an arc or electrica discharge playing between the same, which are is generated by hi h frequency alternating currents.

till another object of my invention is 2 the provision of a method for preventing the concentration of an arc or electrical discharge when operated between electrodes having adjacent surfaces arranged parallel with respect to each other.

Other objects of my invention will be apparent from the following description.

In lamps which are adapted for the projection of motion pictures, it is desirable to provide a concentrated light source and heretofore it has been the practice to provide such a source by arranging two sets of series connected coils,- one. set being positioned behind the other and out of alignment therewith so that the second set of coils fills the interstices or spaces between the elements of the first set in order that the light might be as uniform as possible and constitute a solid light source. In a lamp of this type, special supporting arrangements were necessary in order to prevent the filament from breaking or becoming distorted.

Furthermore, in order to avoid the reversed image of the filament appearing on the screen, the light, source was placed out of 'focus with the films creased efliciency.

sustaining an are or electrical which resulted 1n de-z In the present construction, which forms the subject of my invention, I have provided a lamp in which the light giving source is supported in a simple manner, and furthermore constitutes a solid body. In the accompanying drawing, the view therein illustrates one embodiment of m invention and also shows connected to t e lamp, a source of high frequency current.

The lamp bulb 1 may be of any suitable form and is indicated as of spherical construction. Mounted within the bulb and arranged centrally. with respect thereto are electrodes 2 and 3, each. of which consists of a disk, of circular or other desired shape, of a refractory metal or other incandescible material, such as tungsten, carbon and the like. These electrodes are so arranged that they lie in planes parallel to each other for a purpose to be brought out more fully hereinafter. Each of the electrodes is connected by leading-in wires 4 and 5, respectively,

to the opposite poles of the secondary of a transformer. These leading-in wires serve to support the electrodes 2 and 3 and are disposed within the lamp substantially in the plane of the electrodes so that they do not interfere with the passage of light given off by the electrodes2 and 3. A seal 6 is provided at each of the points where the electrodes pass through the walls of the glass bulb and a re-enforcing sleeve 7 surrounds the leading-in wires to furnish additional stability. Obviously, the leading-in wires may be. otherwise arranged and the electrodes may be suitably supported independently thereof if desired.

The electrodes 2 and 3 maybe of any desired configuration, it being a requisite, however, that they have at least their contiguous faces in substantial parallelism. The container or bulb 1 is filled with a gas inert with respect to the electrode material, such gas being nitrogen, argon, neon, helium andthe like, or mixtures of these atmosphere, that is, it should be capable of discharge between the electrodes.

I have discovered that in order to progases. The pressure of the gas within the envelope may be from one-third to one-half of an vide for uniform heating of the electrodes by means of an are or electrical discharge and in order to prevent concentration of the are or electrical discharge at any point between the electrodes that if the are or electrical discharge is sustained by a high frequency current, the frequency being in the neighborhood of 30,000 and up, that the are or electrical discharge will be uniformly distributed between the electrodes, thus providing for uniform disk illumination. The high frequency energy may be supplied by any well known means and in the drawing there has been illustrated a form of Tesla high frequency transformer for supplying such a current. The high frequency current may be produced as follows: A low frequency alternating current is furnished by the generator 8, which current is stepped up by a' transformer 9 consisting of a primary 10 and secondary 11. The latter has one of its ends connected to one end ofa primar coil 14 and the other end to the primary coll through a spark gap 13. In this circuit is provided a capacity 12 fora purpose which is obvious. The high frequency current set up in the primary 14 is stepped-up by the adjustable secondary 16. The secondary 16 is connected by conductors l7 and 18 to the. leading-in wires 6 and 7 respectively.

In the operation of the device, the lowfrequency alternating current from the generator 8 is stepped-up by transformer 9, converted into high frequency current by the oscillating circuit 12, 13, 15 and stepped up by the Tesla transformer 14 into high frequency alternating current which high frequency current is supplied to the lamp. The current passes between the electrodes 2 and 3 and is uniformly distributed therebetween in the from of an are or electrical discharge by reason of the high frequency of the current.

While I have shown means for supplying high frequency alternating current to the terminals of the lamp, it is to be understood.

that other suitable forms of high frequency current, such as high frequency oscillating currents; may equally well be used.

I have found that a lamp of this character cannotbe operated on a low voltage D. C. or A. 0.. current for the simple reason that the are or electrical discharge would concentrate on some spot on the disk and give non-uniform temperature thereof. Byv

utilizing the high frequency, apparently the are or electrical discharge is prevented from concentrating at such spots and is distributed uniformly between the disks. In order that this uniform distribution may be had, it is desirable-to have the disks or electrodes with their contiguous faces in substantial parallelism.

It will be obvious to those familiar with the disadvantages resident in the present type of motion picture lamp that my lamp overcomes the same by providing a solid, uniformly heated body which gives a constant and steady source of illumination.

Many modifications of my invention may be made and therefore I donot wish to be restricted to the particular embodiment shown in the drawing and described herein.

What is claimed is:

1. The method of preventing an are discharge operated between electrodes of relatively large area from concentrating which comprises generating the arc discharge by means of high frequency current.

2. The method of uniformly heating electrodes of relatively large area by an are dis charge therebetween which comprises generating the'arc discharge by high frequency current.

3. The method of producing light by high frequency current which comprises applying said current between two electrodes having adjacent surfaces of relatively large area in substantial parallelism and providingan arc discharge-sustaining media between said electrodes. v

4. In an incandescent lamp, an envelope having an arc discharge-sustaining media therein, electrodes within said envelope, said electrodes having adjacent surfaces in substantial parallelism, and means for conducting high frequency current to said electrodes,

whereby an arc discharge is uniformly distributed therebetween.

5. In an incandescent lamp, an envelope having an electrical discharge-sustaining media therein, electrodes within said envelope, at least one of said electrodes consisting of a refractory substance, said electrodes Having adjacent surfaces in substantial parallelism, and means for impressing an elec-' trical discharge between said electrodes by high frequencycurrent. I

6. In an incandescent lamp, an envelope having an electrical discharge-sustaining media therein, electrodes within said envelope, said electrodes consisting of refractory substances, and having adjacent surfaces-in substantial parallelism, and means for impressing an electrical discharge between said electrodes b high frequency current.

7. In an incandescent lamp, an envelo having an arc discharge-sustaining me a therein, electrodes within said envelope consisting of tungsten, said electrodes having adjacent surfaces in substantial parallelism,

and means for impressing an arc discharge between said electrodes .by high frequency current.

8. In an incandescent lamp, an envelope having an. arc discharge-sustaining media therein, a pair of electrodes, each consisting of a plate of a refractorv substance, said electrodes being arranged with their adjacent surfaces in substantial parallelism,

and means for impressing an are discharge between said electrodes by high irequency current.

9. In an enclosed are luminous electrode 5 device, an envelope having an arc dischargesust'aining media therein, a pair of electrodes within said envelope, each of saidelectrodes.

consisting of a disk of refractory material,

said disks being arranged in substantial parallelism, and means for sustaining an are 10 discharge between said electrodes by high frequency current. In testimony whereof, I have hereunto subscribed my name this 19th day of February, 1923.

HARVEY CLAYTON RENTSCIIIIR. 

